Bài 17 trang 15 SGK Toán 6 tập 2

Đề bài

Rút gọn:

a)  $\dfrac{3.5}{8.24}$ ;                   b) $\dfrac{2.14}{7.8}$ 

c) $\dfrac{3.7.11}{22.9}$ ;                d) $\dfrac{8.5-8.2}{16}$ ;

e) $\dfrac{11.4-11}{2-13}$ . 

Lời giải chi tiết

a) $\dfrac{3.5}{8.24}=\dfrac{3.5:3}{8.24:3}=\dfrac{5}{8.8}=\dfrac{5}{64}$ .

b) $\dfrac{2.14}{7.8}=\dfrac{2.2.7}{7.2.2.2}=\dfrac{1}{2};$

c) $\dfrac{3.7.11}{22.9}=\dfrac{3.7.11}{2.11.3.3}=\dfrac{7}{2.3}=\dfrac{7}{6};$

d)  $\dfrac{{8.5 - 8.2}}{{16}} = \dfrac{{8.(5 - 2)}}{{2.8}} = \dfrac{{8.3}}{{2.8}} = \dfrac{3}{2}$

e) $\dfrac{{11.4 - 11}}{{2 - 13}} = \dfrac{{11.4 - 11.1}}{{ - 11}}$$\, = \dfrac{{11.(4 - 1)}}{{ - 11}} = \dfrac{{11.3}}{{ - 11}} = \dfrac{3}{{ - 1}} =  - 3.$

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